Bugfix/1156

dbzero/setup.py

@@ -10,7 +10,7 @@
 
 setup(
     name='dbzero',
-    version='0.2.2',
+    version='0.2.3',
     description='DBZero community edition',
     packages=['dbzero'],
     python_requires='>=3.9',

pyproject.toml

@@ -4,7 +4,7 @@ requires = ['meson-python']
 
 [project]
 name = 'dbzero'
-version = '0.2.2'
+version = '0.2.3'
 description = 'A state management system for Python 3.x that unifies your applications business logic, data persistence, and caching into a single, efficient layer.'
 readme = 'README.md'
 requires-python = '>=3.9'

python_tests/test_issues_15.py

@@ -0,0 +1,59 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# Copyright (c) 2025 DBZero Software sp. z o.o.
+
+"""
+Regression test: segfault when db0.find() is called from inside a @db0.memo
+object's __init__ after db0.tags(self).add() has been called on that object.
+
+Minimal sequence:
+  1. Any @db0.memo class TypeA exists
+  2. A @db0.memo class TypeB calls db0.tags(self).add(tag) in __init__,
+     then calls db0.find(TypeA, tag) in the same __init__
+  3. Creating an instance of TypeB → segfault in db0.find
+
+Root cause: db0.tags(self).add() partially registers the in-progress object
+in the tag index; the subsequent db0.find() traverses that index and
+dereferences the not-yet-committed object, causing a null-pointer crash.
+"""
+
+import gc
+import os
+import shutil
+
+import pytest
+import dbzero as db0
+
+from .conftest import DB0_DIR
+
+
+@db0.memo
+class FindTarget:
+    def __init__(self, value: int):
+        self.value = value
+
+
+@db0.memo
+class TaggerAndFinder:
+    def __init__(self):
+        db0.tags(self).add("my-tag")
+        self._results = list(db0.find(FindTarget, "my-tag"))
+
+
+@pytest.fixture()
+def db0_rw_fixture():
+    if os.path.exists(DB0_DIR):
+        shutil.rmtree(DB0_DIR)
+    os.mkdir(DB0_DIR)
+    db0.init(DB0_DIR, read_write=True)
+    db0.open("test_prefix", "rw")
+    yield db0
+    gc.collect()
+    db0.close()
+    if os.path.exists(DB0_DIR):
+        shutil.rmtree(DB0_DIR)
+
+
+def test_find_inside_memo_init_after_tagging_self(db0_rw_fixture):
+    """db0.find() inside a memo __init__ must not segfault after db0.tags(self).add()."""
+    obj = TaggerAndFinder()
+    assert obj._results == []

src/dbzero/object_model/object/ObjectAnyBase.cpp

@@ -102,6 +102,9 @@ namespace db0::object_model
 
     template <typename T, typename ImplT>
     bool ObjectAnyBase<T, ImplT>::hasAnyRefs() const {
+        if (!this->hasInstance()) {
+            return true;
+        }
         return (*this)->hasAnyRefs();
     }